Client likes the version of a video I made for their Facebook page. Now they want dedicated versions for phones and tablets, with captioning on/off options. Never made anything specifically for phones before - what's the workflow and codecs used?

Both Vimeo and Youtube work well as "servers" for videos and give you various options to control access, whether by password or making the videos not searchable. I use compressor now with the 1080 p setting for online videos and that seems to work fine.

Once on Youtube or Vimeo, they can be accessed by various devices (phones, iPads, laptops etc) seamlessly.

I actually find the direct submission mechanism a bit limited compared to the additional options you have on Vimeo/YouTube. But if you want to just blast a bunch of stuff onto those sites, it can be the path of least resistance.